FTP Introduces the UPD Drive Velt Tensioner Pulley. Upgrade your Failure Prone PLASTIC Tensioner Drive Belt pulley with our Billet Aluminum factory replacement Pulley with High Speed ZZ Rated Bearing. This Pulley is a Direct Fit in the Stock location and is LESS than the cost of a factory replacement PLASTIC Tensioner Pulley. Must have for any Stock or Modified M113K Engine.